The long-term objective of this research is to develop technology and devices for the preservation and drying of porcine bioprosthetic or human allograft heart valves which allows storage in a nonfrozen state (4 degrees-22 degrees). Once rehydrated, the potential advantages of such valves would be longer and more convenient storage pregraft, and longer life spans and reduced thromboembolytic risk postgraft. The potential disadvantage might be well-preserved antigenicity sufficient to elicit immune rejection. Porcine heart valves will be preserved by freezing and molecular distillation drying. After storage at a temperature above freezing, these dry valves will be rehydrated and analyzed for structural degeneration using scanning and transmission electron microscopy. Collagen biodegradation in the valves will be determined by residual hydroxyproline content. Calcification will be determined by atomic absorption analyses after implantation for 21 days in young rats. Later Phase II studies in young sheep will determine whether the early calcification of preserved heart valves is prevented by the quality of the structural and biochemical preservation of the valves. We will then test LifeCell-preserved heart valves in animal models, including determinations of the efficacy of seeding the valves with endothelium postpreservation, and attempts to preserve the viability of the whole valves.